194 ME. E. T. NEWTON ON THE VERTEBEATE [May 1 894, 



? Lepus cuniculus. (Rabbit.) — Several portions of tibiae certainly 

 belong to the common rabbit and to young individuals, but there is 

 much doubt as to their being contemporaneous with the other 

 remains with which they are now associated. The burrowing habits 

 of the rabbit make it probable that these remains belong to a later 

 period. The rabbit is a South European form, and although now 

 abundant in many parts of Central Europe and in Britain, is probably 

 not indigenous to any area north of the Alps. 



Lagomys pusillus. (Pika or Tailless Hare.) PI. XL fig. 6. — 

 The left ramus of a lower jaw, wanting the articular process and the 

 anterior cheek-tooth, leaves no doubt as to the presence of Lagomys 

 in this fissure. The recent species of the genus exhibit a remarkable 

 similarity in the pattern of their teeth, and in absolute size there is 

 less difference than might be expected from the variations in this 

 respect observable in the skulls and skeletons of the different species. 

 In size, however, as well as in the length of the entire row of five 

 cheek-teeth (6*7 millim.), the fossil comes nearest to Lagomys 

 pusillus. The complex anterior, or penultimate, premolar is wanting, 

 but the alveolus shows that its grinding surface had a triangular 

 form. The three intermediate grinders are alike, and each has an 

 anterior and a posterior prism of dentine, surrounded by enamel, 

 which are as nearly as possible of the same size ; the last molar is 

 very small, and consists of a single prism. The remains of La- 

 gomys, found in British Caves, were referred by Owen to a new 

 species, L. spelceus, but are now generally included in the species 

 L. pusillus ; and seeing that the jaw from the Ightham fissure 

 agrees best with the same living form, there is no hesitation 

 in referring it also to L. pusillus. This species is at the present day 

 living in the southern districts of the Volga and Ural Mountains, 

 as well as in Southern Siberia as far east as the liiver Obi. 



Spermophilus. — Portions of six right mandibular rami, the upper 

 parts of a cranium, parts of two humeri each with an epicondylar 

 foramen, and parts of four ulnae are referred to this genus. Un- 

 fortunately the parts preserved, including two cheek-teeth, are not 

 sufficient for specific identification. All these remains seem to be 

 rather smaller than those from Erith, which have been named 

 S. erythrogenoides, but it is quite possible that they may belong to 

 that species. Spermophilus is not now living in Britain. 



Mus sylvaticus. (Long-tailed Field-Mouse.) PI. XL fig. 7. — 

 About forty lower-jaw rami and portions of four skulls are referred to 

 this species. Eour of the rami have the anterior cheek-teeth in place, 

 and these show the deep longitudinal groove, with an anterior and 

 two outer accessory cusps similar to those of Mus sylvaticus, except 

 that the more anterior of the outer accessory cusps is compressed 

 and apparently more definitely separated from the paired cusps. But 

 as there is some variation to be seen in this respect in the teeth of 

 Mus sylvaticus, and sometimes there is even an additional accessory 

 cusp, it would scarcely be justifiable to separate these fossils from 



